NDP-081
Interannual Variability in Global Soil Respiration
on a 0.5 Degree Grid Cell Basis (1980-1994)
Contributed by:
James W. Raich (1), Christopher S. Potter (2), and Dwipen Bhagawati (3)
(1)Department of Ecology, Evolution, and Organismal Biology
Iowa State University
Ames, IA 50011 USA
Email: jraich@iastate.edu
(2) Ecosystem Science and Technology Branch
NASA Ames Research Center
MS 242-2
Moffett Field, CA 94035 USA
(3) Department of Civil and Construction Engineering
Iowa State University
Ames, IA 50011 USA
Prepared by L.M. Olsen.
Carbon Dioxide Information Analysis Center
Date Published: August 2003
The Carbon Dioxide Information Analysis Center is a part of the
Environmental Sciences Division of the Oak Ridge National Laboratory (ORNL)
and is located in Oak Ridge, Tennessee 37831-6335. The ORNL is managed by
UT-Battelle, LLC for the U.S. Department of Energy
under contract DE-AC05-00OR22725.
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CONTENTS
ABBREVIATIONS
ABSTRACT
1. BACKGROUND INFORMATION
2. DATA CHECKS PERFORMED BY CDIAC
3. REFERENCES
4. HOW TO OBTAIN THE DATA AND DOCUMENTATION
5. LISTING OF FILES PROVIDED
6. DESCRIPTION OF THE DOCUMENTATION FILE
7. DESCRIPTION, FORMAT, AND PARTIAL LISTINGS OF THE DATA FILES
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ABBREVIATIONS
CO^2 = Carbon Dioxide
CDIAC = Carbon Dioxide Information Analysis Center
FTP = file transfer protocol
QA = quality assurance
GIS = geographic information system
NetCDF = network common data form
ARC/INFO is a registered trademark of the Environmental Systems Research
Institute, Inc., Redlands, CA 92372.
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ABSTRACT
Raich, J. W., C. S. Potter, and D. Bhagawati. 2002. Interannual variability
in global soil respiration, 1980-94. Global Change Biology 8:800-812. doi:
10.3334/CDIAC/lue.ndp081
We used a climate-driven regression model to develop spatially resolved
estimates of soil-CO^2 emissions from the terrestrial land surface
for each month from January 1980 to December 1994, to evaluate the effects of
interannual variations in climate on global soil-to-atmosphere CO^2
fluxes. The mean annual global soil-CO^2 flux over this 15-y period
was estimated to be 80.4 (range 79.3-81.8) Pg C. Monthly variations in global
soil-CO^2 emissions followed closely the mean temperature cycle of
the Northern Hemisphere. Globally, soil-CO^2 emissions reached their
minima in February and peaked in July and August. Tropical and subtropical
evergreen broad-leaved forests contributed more soil-derived CO^2 to
the atmosphere than did any other vegetation type (~30% of the total) and
exhibited a biannual cycle in their emissions. Soil-CO^2 emissions
in other biomes exhibited a single annual cycle that paralleled the seasonal
temperature cycle. Interannual variability in estimated global soil-CO^2
production is substantially less than is variability in net carbon uptake by
plants (i.e., net primary productivity). Thus, soils appear to buffer
atmospheric CO^2 concentrations against far more dramatic seasonal
and interannual differences in plant growth. Within seasonally dry biomes
(savannas, bushlands, and deserts), interannual variability in soil-CO^2
emmissions correlated significantly with interannual differences in
precipitation. At the global scale, however, annual soil-CO^2 fluxes
correlated with mean annual temperature, with a slope of 3.3 Pg C/Y per degree
Celsius. Although the distribution of precipitation influences seasonal and
spatial patterns of soil-CO^2 emissions, global warming is likely
to stimulate CO^2 emissions from soils.
The user may view and print the body of this publication (Raich, J. W., C. S.
Potter, and D. Bhagawati. 2002. Interannual variability in global soil
respiration, 1980-94. Global Change Biology 8:800-812) by downloading file
PCB2002.pdf from the ftp area (this file has been reproduced with permission
of Blackwell Science LTD). The file can be reviewed using the free Adobe (TM)
Acrobat (Tm) Reader software available from
http://www.adobe.com/acrobat/readstep.html.
Keywords: Carbon release, climate change, global carbon cycle, global warming,
model, soil carbon dioxide emissions.
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NDP-081 includes the following data and documentation files:
Descriptive text file (ndp081.txt).
Compressed archive of ASCII format of monthly grids (monthly_dat.tar.gz).
Compressed archive of ARC/INFO export file (.e00) format of monthly grids
(monthly_e00.tar.gz).
Compressed archive of ASCII format of monthly means grids (monthly_means_dat.tar.gz).
Compressed archive of ARC/INFO export file (.e00) format of monthly means grids
(monthly_means_e00.tar.gz).
Compressed archive of ASCII format of daily grids* (daily_dat.tar.gz).
Compressed archive of ARC/INFO export file (.e00) format of daily grids*
(daily_e00.tar.gz).
ASCII format of land cover grid (landcvr3.dat).
Text file listing the classes included in the land cover grid (landcvr3.txt).
ARC/INFO export file (.e00) format of land cover grid (landcvr3.e00).
ASCII format of land area grid (halfarea.dat).
ARC/INFO export file (.e00) format of land area grid (halfarea.e00).
Compressed netCDF file of monthly grids (sr_total_0.5degree.nc.gz).
Compressed netCDF file of daily* grids (sr_daily_0.5degree.nc.gz).
Header file for monthly grids (netCDF companion) (sr_daily_0.5degree.header).
Header file for daily* grids (netCDF companion) (sr_daily_0.5degree.header).
C Program used to create netCDF files from the original data (netCDF companion)
(create_netcdf.c).
Graphic map, "Mean Annual Soil-CO^2 Emissions", (map_yrmn.gif).
Graphic map, "Global Soil-CO^2 Emissions-January", (mean01.gif).
Graphic map, "Global Soil-CO^2 Emissions-February", (mean02.gif).
Graphic map, "Global Soil-CO^2 Emissions-March", (mean03.gif).
Graphic map, "Global Soil-CO^2 Emissions-April", (mean04.gif).
Graphic map, "Global Soil-CO^2 Emissions-May", (mean05.gif).
Graphic map, "Global Soil-CO^2 Emissions-June", (mean06.gif).
Graphic map, "Global Soil-CO^2 Emissions-July", (mean07.gif).
Graphic map, "Global Soil-CO^2 Emissions-August", (mean08.gif).
Graphic map, "Global Soil-CO^2 Emissions-September", (mean09.gif).
Graphic map, "Global Soil-CO^2 Emissions-October", (mean10.gif).
Graphic map, "Global Soil-CO^2 Emissions-November", (mean11.gif).
Graphic map, "Global Soil-CO^2 Emissions-December", (mean12.gif).
*Note: one daily grid exists for each month of record between January 1980
and December 1994.
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1. BACKGROUND INFORMATION
The authors estimated the seasonal and spatial distribution of global soil-CO^2
emissions following the regression based modeling approach of Raich and Potter
(1995) This database, therefore, contains global, spatially explicit
(0.5-degree grid cells) and temporally explicit model output of soil-CO^2
emissions. The calculated emissions include the respiration of both soil
organisms and plant roots.
Please note that NDP-081 is an update to DB1015. Specifically, DB1015 used
long-term climate data as model input while NDP-081 utilizes new climate and
land cover data files. Please refer to Raich et al. 2002,(provided with
permission from Blackwell Science Ltd.) for more information.
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2. DATA CHECKS PERFORMED BY CDIAC
One of the roles of the Carbon Dioxide Information Analysis Center (CDIAC) is
quality assurance (QA) of data. The QA process is an important component of
the value-added concept of assuring accurate, usable information for
researchers, because data received by CDIAC are rarely in condition for
immediate distribution, regardless of source. The following summarizes the QA
checks performed on the data files:
1. Calculated the mean annual global soil-CO^2 flux over the 15 year period
(1980-1994) using the monthly grids. The value (80.4 Pg) was in agreement with
the published values of Raich et al. 2002. Note: cells that were assigned a
land cover value of 14 (polar ice and rockland) were assigned a value of zero
in the monthly and daily data files provided by CDIAC (following the methods
used by Raich et al. 2002).
2. Calculated the mean annual global soil-CO^2 flux (see above) by land cover
type (DeFries et al. 1998). The values were in agreement with those published
in Raich et al. 2002.
3. Used the daily data grids to derive monthly data grids by multiplying them
by landarea (halfarea.e00 or halfarea.dat) and number of days per month
(methods described by author). When these derived grids were compared with
the monthly grids included with this data set, they differed slightly. These
differences are probably the result of varying levels of precision in the
software used to create them.
Note: 1 Pg C = 1.e15 g C
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3. REFERENCES
DeFries, R.S, M. Hansen, J.R.G. Townshend, and R. Sohlberg. 1998. Global
land cover classifications at 8 km spatial resolution: the use of training
data derived from landsat imagery in decision tree classifiers.
International Journal of Remote Sensing 19:3141-3168.
Raich, J.W. and C.S. Potter and D. Bhagawati. 2002. Interannual variability
in global soil respiration, 1980-1994. Global Change Biology 8:800-812.
Raich, J. W. and C. S. Potter. 1995. Global patterns of carbon dioxide
emissions from soils. Global Biogeochemical Cycles 9(1)23-36.
Raich, J.W. and C.S. Potter. 1995. Global patterns of carbon dioxide
emissions from soils on a 0.5 degree grid cell basis. DB1015, Available
on-line [http://cdiac.ornl.gov/epubs/db/db1015/db1015.html]. Carbon
Dioxide Information Analysis Center, U.S. Department of Energy, Oak Ridge
National Laboratory, Oak Ridge, TN, U.S.A.
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4. HOW TO OBTAIN THE DATA AND DOCUMENTATION
These data may be used with a raster geographic information system (GIS) or
non-GIS database systems. This database (NDP-081) is available free of charge
from CDIAC. The files are available, via the Internet, from CDIAC's
World-Wide-Web site (http://cdiac.ornl.gov), or from CDIAC's anonymous file
transfer protocol (FTP) area (cdiac.ornl.gov) as follows:
1. FTP to cdiac.ornl.gov (128.219.24.36).
2. Enter "ftp" as the user id.
3. Enter your electronic mail address as the password (e.g., fred@zulu.org).
4. Change to the directory "pub/ndp081" (i.e., use the command "cd
pub/ndp081").
5. Set ftp to get ASCII files by using the ftp "ascii" command.
6. Retrieve the ASCII database documentation file by using the ftp "get
ndp081.txt" command.
7. Set ftp to get compressed data files by using the ftp "binary" command.
8. Retrieve the compressed data files by using the ftp "mget *.gzip" command.
9. Exit the system by using the ftp "quit" command.
For non-Internet data acquisitions (e.g., floppy diskette or CD-ROM) or
for additional information, contact:
Carbon Dioxide Information Analysis Center
Oak Ridge National Laboratory
P.O. Box 2008
Oak Ridge, Tennessee 37831-6335, U.S.A.
Telephone: 1-865-574-3645
Telefax: 1-865-574-2232
E-mail: cdiac@ornl.gov
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5. LISTING OF FILES PROVIDED
This database consists of twelve data files (*.dat), four text
files (*.txt) and thirteen graphics files (*gif)..
Please note: data is provided in three different formats as a courtesy to
our users (ASCII, ESRI export, and netCDF).
Data files include:
1. monthly_dat.tar.gz
2. monthly_e00.tar.gz
3. monthly_means_dat.tar.gz
4. monthly_means_e00.tar.gz
5. daily_dat.tar.gz
6. daily_e00.tar.gz
7. halfarea.dat
8. halfarea.e00
9. landcvr3.dat
10. landcvr3.e00
11. sr_total_0.5degree.nc.gz
12. sr_daily_0.5degree.nc.gz
Text files include:
1. ndp081.txt
2. landcvr3.txt
3. sr_total_0.5degree.header
4. sr_daily_0.5degree.header
5. create_netcdf.c
Graphics files include:
1. map_yrmn.gif
2. mean01.gif
3. mean02.gif
4. mean03.gif
5. mean04.gif
6. mean05.gif
7. mean06.gif
8. mean07.gif
9. mean08.gif
10. mean09.gif
11. mean10.gif
12. mean11.gif
13. mean12.gif
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6. DESCRIPTION OF THE DOCUMENTATION FILES
The ndp081.txt file is an ASCII text equivalent of this document.
The landcvr3.txt file is a key to the land cover classification codes used in
the grid landcvr3.
The sr_total.0.5 degree.header is a companion to the netCDF file
sr_total_0.5degree.nc.gz.
The sr_daily.0.5 degree.header is a companion to the netCDF file
sr_daily_0.5degree.nc.gz.
Create_netcdf.c is the C program used to create the netCDF files from the
original data files.
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7. DESCRIPTION, FORMAT, AND PARTIAL LISTINGS OF THE DATA FILES
Twelve data files are provided with this data package. All grids are global
in extent and are unprojected (decimal degrees).
1. monthly_dat.tar.gz: grid files of MONTHLY predicted soil CO^2-C emissions
for every month from January 1980 to December 1994.
Units are MgC/gridcell/month. The gzip and tar
utilities were used to compress these files in UNIX.
This archive contains 180 monthly data files in ASCII
format (Please see section below for description).
The first two digits in the filename refer to the year
and the last two digits refer to the month.
2. monthly_e00.tar.gz: grid files of MONTHLY predicted soil CO^2-C emissions
for every month from January 1980 to December 1994.
Units are MgC/gridcell/month. The gzip and tar
utilities were used to compress these files in UNIX.
This archive contains 180 monthly data files in ESRI
export format (*e00) (Please see section below for
description). The first two digits in the filename
refer to the year and the last two digits refer to
the month.
3. monthly_means_dat.tar.gz: grid files containing MONTHLY MEAN soil CO^2-C
emissions as calculated from the monthly data files
described above (Jan. 1980-Dec. 1994). Units are
MgC/gridcell/month. The gzip and tar utilities were
used to compress these files in UNIX. This archive
contains 12 data files in ASCII format (Please see
section below for description). The last two digits
in the filename refer to the month.
4. monthly_means_e00.tar.gz: grid files containing MONTHLY MEAN soil CO^2-C
emissions as calculated from the monthly data files
described above (Jan. 1980-Dec. 1994). Units are
MgC/gridcell/month. The gzip and tar utilities were
used to compress these files in UNIX. This archive
contains 12 data files in ESRI export format (*e00)
(Please see section below for description).
The last two digits in the filename refer to the month.
5. daily_dat.tar.gz: grid files containing predicted DAILY soil CO^2-C
emissions representing every month from January 1980
through December 1994 (one daily file per month).
Units are gC/m^2/day. The gzip and tar utilities were
used to compress these files in UNIX. This archive
contains 180 data files in ASCII format (Please see
section below for description). The first two digits
in the filename refer to the year and the last
two digits refer to the month.
6. daily_e00.tar.gz: grid files containing predicted DAILY soil CO^2-C
emissions representing every month from January 1980
through December 1994 (one daily file per month).
Units are gC/m^2/day. The gzip and tar utilities were
used to compress these files in UNIX. This archive
contains 180 data files in ESRI export format (*e00)
(Please see section below for description). The first
two digits in the filename refer to the year and
the last two digits refer to the month.
7. sr_total_0.5degree.nc.gz: NetCDF file composed of grids depicting
MONTHLY predicted soil CO^2-C emissions
for every month from January 1980 to December 1994.
Units are MgC/gridcell/month. The gzip utility
was used to compress the netCDF file in UNIX.
(Please see section below for format description).
8. sr_daily_0.5degree.nc.gz: NetCDF file is composed of grids depicting
DAILY predicted soil CO^2-C emissions representing
every month from January 1980 through December 1994.
Units are gC/m^2/day. The gzip utility was
used to compress the netCDF file in UNIX.
(Please see section below for format description).
9. halfarea.dat: a 0.5 degree lat/lon file with grid cell area information.
Units are km^2/grid cell. This file was used by the
authors in the global summation of soil emissions.
This file is in ASCII format (Please see section below
for description).
10. halfarea.e00: a 0.5 degree lat/lon file with grid cell area information.
Units are km^2/grid cell. This file was used by the
authors in the global summation of soil emissions.
The file is in ESRI export format (*e00) (Please see
section below for description).
11. landcvr3.dat: a 0.5 degree land cover classification based on Defries
et al. (1998). This file was used by the authors in
the global summation of soil emissions by land cover
type. The file is in ASCII format (Please see section
below for description).
12. landcvr3.e00: a 0.5 degree land cover classification based on Defries
et al. (1998). This file was used by the authors in
the global summation of soil emissions by land cover
type. The file is in ESRI export format (*e00).
(Please see section below for description).
FILE FORMATS:
ASCII GRID: Each file contains a single ASCII array with integer values.
Coordinates listed below are in decimal degrees.
The ASCII file consists of header information containing a set of keywords,
followed by cell values in row-major order. The file format is:
NCOLS xxx
NROWS xxx
XLLCORNER xxx
YLLCORNER xxx
CELLSIZE xxx
{NODATA_VALUE xxx}
row 1
row 2
.
.
.
row n
where xxx is a number, and the keyword NODATA_VALUE is optional and defaults to
-9999. Row 1 of the data is at the top of the grid, row 2 is just under row 1
and so on. The end of each row of data from the grid is terminated with a
carriage return in the file.
These six lines (header) appear in all of the data files, e.g.:
ncols 720
nrows 360
xllcorner -180
yllcorner -90
cellsize 0.5
NODATA_value -9999
To import this file into ArcInfo use the following command at an ARC prompt:
ASCIIGRID {INT | FLOAT}
Arguments
- the ASCII file to be converted.
- the name of the grid to be created.
{INT | FLOAT} - the data type of the output grid.
INT - an integer grid will be created.
FLOAT - a floating-point grid will be created.
Note: This data can also be imported into ArcView (with Spatial Analyst) and
ArcGis as ASCII Raster data.
ARC/INFO EXPORT FILE (*.E00) : is a proprietary format that can be imported into
ARC/INFO GRID using the following command at an ARC prompt:
IMPORT

Arguments

- GRID
- the name of the *e00 file to be converted
- a user specified output file
NetCDF:
Network Common Data Form (netCDF) is an interface for array-oriented data
access, and is commonly utilized by climate modelers. Please see
http://www.unidata.ucar.edu/packages/netcdf/ for a complete description
of NetCDF files. To obtain a list of available software for viewing
and manipulating netCDF files, please see
http://www.unidata.ucar.edu/packages/netcdf/software.html. Please see
the file create_netcdf.c if you are interested in how the netCDF files were
created from the original data files.